Instead of making Asterisk do this work, wouldn't it make more sense to just have a "smart" ethernet sniffer that handled the whole transaction? I have no details on it, but I would guess that the previously-named "Carnivore" project here in the USA and it's related brethren elsewhere are probably capable of such intercept if they have visibility of all SIP setup and RTP packets.
Extracting those features out into a commercial product would not be terribly difficult, and I strongly suspect if I spent a few hours with Google I would find a vendor already selling such a product for an eye-popping sum of money.
That being said against modifying Asterisk, here is an agreeing view:
Asterisk already has the ability to record specific conversations with fairly simple dialplan logic, as I've demonstrated with my sample files. A clever programmer could modify Dave Troy's "ZapScan" application to use any channel type, I'm sure, and relay that information out to an alternate channel that turned voice streams to .mp3 codec form to be streamed to some local relay agent (shoutcast, icecast) and from there across a VPN to Langley, Linthicum, or your local sheriff's office. Since Asterisk can record things already, that's a "given". With 250gb disks now commonplace, I can fit a terabyte into a 1u PC. Let's see... with GSM files being ~100kb per minute of two-leg conversations, and let's say 1 entire PRI at 50% usage (yes, that's a high Erlang, but this is back-of-napkin) that turns into (very roughly) almost two years of recording of every single conversation on a PRI.
I'm sure someone could make a tidy sum of money deploying this type of system, even if they gave the modifications back to the community as per the GPL license as they are obligated to do if it becomes a "resold product". A T400P card in a good-quality rackmount PC (total cost for both, with a terabyte of disk: ~$5200) could become a completely "transparent" monitoring system that could be inserted at the carrier's office or even closer, and the subscriber to the PRI would never know it was there. As long as there was Internet access somehow, this could be monitored and commanded remotely. Law enforcement is always willing to pay good money to technical firms to install stuff, even if it's open-source.
In short: Asterisk is already an almost-ideal call recording platform with no modifications. With few modifications, it could easily work as a "live" intercept system with incredible flexibility.
(PS: I am a consultant, so any law enforcement agencies reading this should feel free to shower me with money.)
(PPS: Ethical note - I am a big fan of strong crypto, individual rights, and a rollback of many of the current "basic rights" encroachments that have occurred in the recent years in the US (and even in the EU.) However, I also recognize the completely legitimate and necessary use of wiretaps in circumstances that are legally warranted, and I believe that law enforcement should use every tool that they are legally allowed.)
JT
My 5 cents ...
Since the ideal situation would be real-time monitoring then maybe a more effective solution would be to sample/duplicate the packets in the IP layer rather than expecting Asterisk to perform yet another auxiliary function.
Cisco like most vendors are in a position were they have to provide Lawful Intercept capabilities within their own (VoIP & IP) platforms very quickly to support the new European regulations. As a result of this a new feature will soon be available in Cisco IOS allowing routers (or AS5300's for that matter) to copy all inbound/outbound packets onto another interface or even re-write the destination address providing the capability to 'sniff' all IP (RTP/SIP) packets and route them off to another box.
That other box could be another instance of Asterisk dedicated for the purpose or purely a replicated real-time packet stream routed directly to the authorities intercept platforms.
-----Original Message----- From: Andrew Joakimsen [mailto:[EMAIL PROTECTED] Sent: 12 September 2003 04:33 To: [EMAIL PROTECTED]> Subject: RE: [Asterisk-Users] Legal Interception - tapping > > > -----Original Message-----> From: [EMAIL PROTECTED] [mailto:asterisk-users- > [EMAIL PROTECTED] On Behalf Of Brian West > Sent: Thursday, September 11, 2003 10:20 PM > To: [EMAIL PROTECTED] > Subject: RE: [Asterisk-Users] Legal Interception - tapping > > pamAssassin 2.55 (1.174.2.19-2003-05-19-exp) > > > issue. If they are using Asterisk is it not possible to record calls > > automatically. I have not reviews the CALEA requirements, must access be > > Yes it is very possible to record calls with *. I record all in and > outbound calls. > > bkw
I phrased that incorrectly, I have way too much email to look at....
I know it is possible to record calls, it will record them to a directory you define on the server. But are you required to provide archives/recordings of the calls or permit real-time tapping?> >
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